CN214422459U

CN214422459U - Water treatment system

Info

Publication number: CN214422459U
Application number: CN202021137102.5U
Authority: CN
Inventors: S·拉森
Original assignee: Siemens Energy Inc
Current assignee: Lummus Technology LLC
Priority date: 2020-06-18
Filing date: 2020-06-18
Publication date: 2021-10-19
Anticipated expiration: 2030-06-18

Abstract

The utility model relates to a water treatment system for reduce and produce the total carbon consumption in the low chemical oxygen demand treatment stream. In certain aspects, the systems described herein include an oxidation stage (e.g., a stage that utilizes ozone, hydrogen peroxide, ultraviolet light, or a combination thereof) between the first activated carbon stage and the second activated carbon stage to reduce the overall carbon consumption within the associated system.

Description

Water treatment system

Technical Field

The present invention relates to treatment systems, and in particular to a system for reducing the total activated carbon consumption for producing a low Chemical Oxygen Demand (COD) treatment stream.

Background

Wastewater streams are typically treated by a variety of processes to remove organics, solids, and any other undesirable contaminants therefrom. For example, the wastewater stream may be contacted with activated carbon for a period of time effective to remove an amount of Chemical Oxygen Demand (COD) therefrom. In some cases, the activated carbon is further combined with biological materials suitable for removing readily biodegradable organics from wastewater streams. Wastewater streams require lower maximum allowable levels of COD and similar contaminants worldwide. To achieve these lower levels (e.g., less than 50 mg/L COD), in many cases, two activated carbon stages (activated carbon in two or more separate vessels) may be provided in series to achieve the desired lower COD concentration.

However, having two activated carbon stages requires a large overall carbon consumption or total carbon consumption in the associated system and process, which requires a large amount of material cost, storage and transportation. To reduce the total carbon consumption, the spent activated carbon from each stage may be regenerated by Wet Air Oxidation (WAO) at high temperature, high pressure and in the presence of an oxygen-containing gas. This recycling of carbon will reduce the amount of fresh carbon required. However, the total carbon consumption required to reduce COD levels in a two-stage system to below the maximum allowable limit for COD levels for most commercial applications is generally too large for a single WAO unit. Due to the proliferation of large industrial park wastewater complexes or integrated refineries and reduced emission limits, the WAO unit has become too large or requires two units. Repeated addition of large amounts of fresh activated carbon and/or addition of a second WAO unit can significantly increase the cost of the associated system or process.

SUMMERY OF THE UTILITY MODEL

The present inventors have developed systems and processes for reducing the total carbon consumption required to produce low COD treated water. In certain aspects, the systems and processes described herein include an oxidation stage (e.g., an oxidation stage that utilizes ozone, hydrogen peroxide, ultraviolet light, or any other suitable oxidant/oxidizing agent, or combination thereof) between the first activated carbon stage and the second activated carbon stage to reduce the overall carbon consumption within the associated system or process. Without wishing to be bound by theory, it is believed that oxidation between the two activated carbon stages can significantly reduce the total activated carbon required to achieve a low COD (< 50 mg/L) of the treated wastewater. In certain embodiments, the presence of an oxidation grade reduces the total carbon consumption by 25% (by mass) or more.

According to another aspect, the systems and processes described herein utilize two or more carbon stages, each carbon stage comprising a combination of activated carbon and biomass, to reduce Chemical Oxygen Demand (COD) in a wastewater stream. The presence of an oxidation stage, which oxidizes a treated stream from the first carbon stage (optionally including biomass), results in an increase in the fraction of biodegradable COD and/or an overall decrease in COD relative to the first treated stream. This allows the COD concentration to be more easily reduced in the second carbon stage by the biomass therein, thereby reducing the carbon required in the second stage and the overall carbon consumption of the system.

According to an aspect of the present invention, there is provided a water treatment system, comprising: (i) a first carbon stage comprising a first vessel containing at least a first amount of activated carbon effective to reduce a first amount of Chemical Oxygen Demand (COD) from the wastewater stream and produce a first treated stream having a first reduced amount of COD; (ii) an oxidation unit disposed downstream of the first carbon stage, the oxidation unit configured to oxidize a second amount of COD from the first treated stream and produce a second treated stream having a second reduced amount of COD; and (iii) a second carbon stage downstream of the oxidation unit comprising a second vessel containing at least a second amount of activated carbon effective to reduce a third amount of Chemical Oxygen Demand (COD) from the second treated stream and produce a third treated stream having a third reduced amount of COD equal to or below the predetermined concentration limit.

According to another aspect, there is provided a water treatment process comprising: (i) generating a first treated stream having a first reduced amount of COD via contacting the wastewater stream with a first amount of activated carbon; (ii) generating a second treated stream having a second reduced amount of COD via subjecting the first treated stream to an oxidation process; and (iii) producing a third treated stream having a third reduced amount of COD equal to or below the predetermined concentration limit via contacting the second treated stream with at least a second amount of activated carbon; wherein the oxidation process reduces the total carbon consumption required to bring the COD at or below a predetermined concentration limit relative to a process without an oxidation step.

According to another aspect, there is provided a water treatment system comprising: (i) a first bioreactor comprising a first amount of activated carbon and a first amount of biomass, the first bioreactor configured to remove a first amount of Chemical Oxygen Demand (COD) from a wastewater stream introduced thereto and produce a first treated stream comprising a first reduced amount of COD and a first solids fraction comprising the first amount of activated carbon and biomass; (ii) a first separator in fluid communication with the first bioreactor, the first separator configured to separate the first treated stream from the first solids portion; (iii) an oxidation unit in fluid communication with the first separator, the oxidation unit configured to oxidize an amount of COD in the first treated stream and produce a second treated stream comprising a second reduced amount of COD; (iv) a second bioreactor in fluid communication with the oxidation unit comprising a second amount of activated carbon and a second amount of biomass, the second bioreactor configured to remove a third amount of COD from a second treated stream to produce a third treated stream comprising a reduced amount of COD and a second solids portion comprising the second amount of activated carbon and biomass; and (v) a second separator in fluid communication with the second bioreactor, the second separator configured to separate the third treated stream from the second solids portion.

According to another aspect, there is provided a water treatment process comprising: (i) treating a wastewater stream comprising an amount of Chemical Oxygen Demand (COD) therein in a first bioreactor comprising a first amount of activated carbon and a first amount of biomass; (ii) producing a first treated stream comprising a first reduced COD concentration from a first bioreactor; (iii) oxidizing the first treated stream to produce a second treated stream comprising a second reduced COD concentration; (iv) treating the second treated stream in a second bioreactor comprising a second amount of activated carbon and a second amount of biomass; and (v) producing a third treated stream comprising a third reduced COD concentration from the second bioreactor.

Drawings

Fig. 1 illustrates a wastewater treatment system for reducing total carbon consumption in wastewater treatment to low Chemical Oxygen Demand (COD) concentrations in accordance with an aspect of the present invention.

Fig. 2 illustrates an embodiment of a first carbon stage in a system according to an aspect of the present invention.

FIG. 3 illustrates an embodiment of a membrane bioreactor first carbon stage in a system according to an aspect of the present invention.

Fig. 4 illustrates an embodiment of a system carbon stage in a system according to an aspect of the present invention.

Fig. 5 illustrates a wastewater treatment system for reducing total carbon consumption in wastewater treatment to low Chemical Oxygen Demand (COD) concentrations in accordance with another aspect of the present invention.

Fig. 6 illustrates movement of material through a wastewater treatment system according to an aspect of the present invention.

Fig. 7 illustrates a wastewater treatment system according to an aspect of the present invention, further comprising a wet air oxidation unit.

Fig. 8 illustrates a wastewater treatment system according to another aspect of the present invention, further comprising a wet air oxidation unit.

Fig. 9 illustrates a wastewater treatment system according to another aspect of the present invention, further comprising a purification and storage system.

Detailed Description

Referring now to the drawings, FIG. 1 illustrates an embodiment of a water treatment system 10 for treating a wastewater stream 12 including an amount of Chemical Oxygen Demand (COD) therein according to an aspect of the present invention that also reduces the overall carbon requirements of the system. As shown, wastewater stream 12 flows (in flow order) through a first carbon stage 14, an oxidation unit 16, and a second carbon stage 18 to provide a treated stream 20 having an amount of COD below a maximum allowable limit (e.g., ≦ 50 mg/L, and in some embodiments ≦ 30 mg/L). Wastewater stream 12 may refer to any fluid that includes a certain amount of Chemical Oxygen Demand (COD) therein. In certain embodiments, the wastewater stream 12 may comprise a wastewater stream from an industrial, agricultural, or municipal source. In certain embodiments, the COD includes a quantity of organic and inorganic contaminants. Additionally, in certain embodiments, wastewater stream 12 is a wastewater stream that includes biodegradable contaminants (e.g., biodegradable organics) as well as non-degradable organics that are difficult to biodegrade and are preferably removed from stream 12 by activated carbon and/or by oxidation assistance. In particular embodiments, wastewater stream 12 may comprise a waste stream from a petrochemical production or refining process (such as an oil refinery process).

The first carbon stage 14 can include any suitable components in a configuration that utilizes at least an amount of activated carbon that is effective to reduce a first amount of Chemical Oxygen Demand (COD) from the wastewater stream 12 and produce a first treated stream 22 having a first reduced amount of COD. In an embodiment and as shown in fig. 2, to obtain the first treated stream 22, the first carbon stage 14 includes a first vessel 24 in fluid communication with a first separator 28, the first vessel 24 including a first amount of activated carbon 26 therein. As used herein, a container (e.g., 24) may be closed or open, such as by having an open top. The first amount of activated carbon 26 may include Powdered Activated Carbon (PAC), Granular Activated Carbon (GAC), or a combination thereof. Additionally, the first amount of activated carbon 26 is effective to remove a first amount of Chemical Oxygen Demand (COD) from the wastewater stream 12 and produce a first material 30. The first material 30 includes a mixture of the first treated stream 22 and a first solids portion 32, the first solids portion 32 including at least a first amount of activated carbon 26.

In certain embodiments and as shown in fig. 2, a first amount of biomass 34 is also optionally combined or integrated with the activated carbon 26 in the first vessel 24 to reduce an amount of biodegradable COD in the wastewater stream 12. When the first vessel 24 includes a first amount of biomass 34 therein, the first vessel 24 may be referred to as a bioreactor as known in the art, and the solids portion 32 will therefore include activated carbon (used or spent) and biomass. In this case, the first amount of biomass 34 readily degrades the biodegradable COD while the first amount of activated carbon 26 effectively removes an amount of refractory organics in the wastewater stream 12 that is delivered to the first carbon stage 14. As used herein, refractory organics define a class of organics that may be slow or refractory to biodegradation relative to the majority of organics in wastewater stream 12, e.g., as used to determine BOD₅Etc. as defined by the standard methods or the EPA method.

The first amount of biomass 34 can include any suitable population of bacterial microorganisms effective to digest the biodegradable material, including a population of bacterial microorganisms that do so with reduced solid products. Exemplary wastewater treatment with reduced solids products is described in U.S. patent nos. 6,660,163, 5,824,222, 5,658,458, and 5,636,755, each of which is incorporated herein by reference in its entirety. The bacteria may include any bacteria or combination of bacteria suitable for growth under anoxic and/or aerobic conditions. Representative aerobic genera include the bacteria Acinetobacter, Pseudomonas, Acinetobacter, Achromobacter, Flavobacterium, Nocardia, Bdellovibrio, Mycobacterium, Hispanielus (Shpaeotilus), Saccharomycota (Baggiatoa), Thielavia, Leiochrospira (Lecicothrix) and Geotrichum, Nitrobacter, Nitrosomonas and Nitrobacter, and protozoa cilia, Staphylium, Geotrichum and rectocele (Epistylis). Representative hypoxic genera include the denitrifying bacteria Achromobacter, Aerobacter, Alcaligenes, Bacillus, Brevibacterium, Flavobacterium, Lactobacillus, Micrococcus, Proteus, Pseudomonadaceae (Pseudomonas), and Spirobacterium.

Referring again to fig. 2, the first separator 28 is in fluid communication with the first vessel 24 and is configured to receive a first material 30 within one or more input ports in the first separator and then separate the first treated stream 22 (including a first reduced amount of COD from the wastewater stream 12) from a first solids fraction 32 including at least a first amount of activated carbon 26. First separator 28 may include any suitable structure that employs a process that effectively separates first treated stream 22 from solids portion 32. In embodiments, the first separator 28 includes one or more clarifiers, membrane units, combinations thereof, and the like. The first separator 28 also includes at least one outlet from which the separated first process stream 22 exits and is conveyed to the oxidation stage 16.

In certain embodiments, the first separator 28 comprises a clarifier, as is well known in the art. In other embodiments, the first separator 28 comprises a dissolved gas unit, a hydrocyclone, or a membrane unit, which may for example comprise one or more porous or semi-permeable membranes. In embodiments, the membrane unit comprises a microfiltration membrane or an ultrafiltration membrane as known in the art. In addition, the membrane of the membrane unit may have any configuration suitable for its intended application, such as a sheet or a hollow fiber or a monolith. Further, the membrane may have any suitable porosity and/or permeability for its intended application. Still further, the membrane may have any suitable shape and cross-sectional area, such as, for example, a square, rectangular, or cylindrical shape. In one embodiment, the membrane has a rectangular shape. In addition, the one or more membranes may be positioned, for example vertically, in the treatment zone of the membrane unit so as to be completely submerged by the wastewater stream 12. In certain embodiments, the first vessel 24 and the first separator 28 comprise separate, individual components. However, it should be understood that the present invention is not limited thereto.

In other embodiments and as shown in fig. 3, the first vessel 24 (including the activated carbon 26 and optional biomass 34) may be integrated with the first separator 28 and include a single component, such as a membrane bioreactor 36 as is known in the art. In this case, the membrane bioreactor 36 of the first carbon stage 14 is configured to receive the wastewater stream 12, reduce an amount of COD in the wastewater stream 12 via contact with the first amount of activated carbon 26 and biomass 34 (if present), and separate the resulting first treated stream 22 from the first material 32 comprising activated carbon (and optionally biomass) via one or more membranes contained within the membrane bioreactor 36 as described herein. The first treated stream 22 may likewise exit the outlet of the membrane bioreactor 36 and be directed to the oxidation stage 16 (FIG. 1).

Referring again to fig. 1, at oxidation stage 16, oxidation stage 16 may include one or more oxidation units 38, each oxidation unit 38 configured to contain a volume of first treated stream 22 (if desired), and to oxidize an amount of COD in first treated stream 22, thereby producing therefrom a second treated stream 40 including a second reduced amount of COD. The second reduced amount of COD is a reduced amount of COD relative to the first treated stream 22, and thus relative to the wastewater stream 12. Additionally, the oxidation unit 38 includes any suitable vessels and structures for employing ozone, ultraviolet light, hydrogen peroxide, either alone or in any combination, for delivery, such as by using ultraviolet light to enhance the action of hydrogen peroxide, or using any other suitable technique to oxidize contaminants that result in COD in the wastewater stream 12. Thus, in an embodiment, the oxidation process occurs at the oxidation stage 16 by subjecting the stream introduced therein (e.g., the first treated stream 22) to an oxidation process, such as by subjecting the first treated stream 22 to an effective amount of ozone, hydrogen peroxide, ultraviolet light at a suitable wavelength, or any other suitable oxidant/oxidizing agent or combination thereof effective to reduce an amount of COD from the first treated stream 22 and produce therefrom a second treated stream 40 comprising a second reduced amount of COD.

As set forth above, the presence of the oxidation stage 16 significantly reduces the total carbon consumption required to produce a final treatment stream 20 in the system 10 having a COD concentration that is less than a predetermined amount (e.g., less than a strict COD requirement). In embodiments, the (final) treatment stream 20 from a system or process as described herein comprises a COD concentration of 50 mg/L or less, and in particular embodiments 30 mg/L or less. In certain embodiments, the second reduced amount of COD of the second treated stream 40 comprises an increased fraction of biodegradable COD relative to the first treated stream 22 when the first treated stream 22 is subjected to the oxidation process. The increased biodegradable fraction makes the COD more likely to decrease in the second carbon stage 18.

For example, as shown in the embodiment of fig. 4, the second carbon stage 18 may include any suitable configuration as described herein for the first carbon stage 14. For the sake of brevity, each embodiment of the second carbon stage 18 will not be described below; however, it should be understood that any description of the first carbon stage 14 is equally applicable to the second carbon stage 18. The difference between the first carbon stage 14 and the second carbon stage 18 is that: the first carbon stage 14 is disposed upstream of the oxidation stage 16 (oxidation step) and the second carbon stage 18 is located downstream of the oxidation stage in the flow direction of the wastewater 12 being treated.

The second carbon stage 18 can likewise comprise any suitable structure in a configuration that utilizes at least a second amount of activated carbon to contact the stream therein (second treated stream 40) to reduce a third amount of Chemical Oxygen Demand (COD) (relative to the wastewater stream 12) and produce a final treated stream 20 having a third reduced amount of COD. In certain embodiments, the third reduced amount of COD is equal to or below the maximum allowable limit for COD, such as less than 50 mg/L. Similar to the first carbon stage 14, in certain embodiments (as shown in fig. 4), the second carbon stage 18 may similarly include a second container 42 and a second separator 46, with a second amount of activated carbon 44 included in the second container 42. The second amount of activated carbon 44 may include Powdered Activated Carbon (PAC), Granular Activated Carbon (GAC), or a combination thereof.

In addition, a second amount of activated carbon 44 is effective to remove another amount of Chemical Oxygen Demand (COD) from the wastewater stream 12 (now in the form of the second treated stream 40) and produce a second material 48. Like the first material 30, the second material 48 comprises a mixture of the third (final) treated stream 20 and a second solids portion 50, the second solids portion 50 comprising at least a second amount of activated carbon 44. Likewise, the second carbon stage 18 may include a second separator 46 for separating the process stream 20 from a second solids portion 50. As with the first carbon stage 14, a second amount of biomass 52 may also be included in the second vessel 42 for treating readily biodegradable contaminants within the wastewater stream 12. Still further, in an embodiment, the second carbon stage 18 may comprise a membrane bioreactor comprising activated carbon 44 and optionally biomass 52, wherein a plurality of membranes are housed in the membrane bioreactor, as described above.

In view of the above, according to one aspect and as shown in fig. 5, the system 10 may include (in flow order): a first bioreactor 25 comprising a first amount of activated carbon and a first amount of biomass for producing a first material 30; a first separator 28 for separating a first material 30 into a first treated stream 22 and a first solids portion 32; an oxidation stage 16 for oxidizing a component of the first treated stream to produce a second treated stream 40; and a second bioreactor 35 comprising a second amount of activated carbon and a second amount of biomass for producing a second material 48; a second separator 46 for separating a second material 48 into a third (final) treated stream 20 and a second solids portion 50.

According to another aspect, activated carbon (and biomass, if present) may be recycled through the system to limit the need for adding fresh carbon, which would increase overall carbon consumption. Referring to fig. 6, the system 10 may further include a conduit 62 in fluid communication between the second separator 46 and the first vessel 24 for conveying at least a portion of the second solids fraction 50 including activated carbon (and optionally biomass) from the second separator 46 to the first vessel 24. Additionally, in certain embodiments, the system 10 may alternatively or additionally include a conduit 64 in fluid communication between the first separator 28 and the first vessel 24 for conveying at least a portion of the first solids fraction 32 including activated carbon (and optionally biomass) from the first separator 28 to the first vessel 24. Further, in certain embodiments, the system 10 may alternatively or additionally include a conduit 66 in fluid communication between the second separator 46 and the second vessel 42 for conveying at least a portion of the second solids portion 50 including activated carbon (and optionally biomass) from the second separator 46 to the second vessel 42. With any of the

conduits

62, 64, and/or 66, the activated carbon (and optionally biomass) may thus be reused within the system 10.

It will be appreciated that at some point, the activated carbon in the first stage 14 or second stage 18 becomes "spent" -meaning that its ability to adsorb or otherwise remove chemical oxygen demand from the wastewater stream 12 becomes compromised. In accordance with another aspect of the present disclosure, the total carbon consumption of the system 10 may be further minimized via the addition of the WAO 54, which WAO 54 may regenerate the spent carbon from the first carbon stage 14 and/or the second carbon stage 18 and recycle the regenerated carbon to the first carbon stage 14 and/or the second carbon stage 18. Referring now to fig. 7, there is a system 10 as previously described herein that includes a first carbon stage 14, an oxidation stage 16, and a second carbon stage 18 in the flow direction of the wastewater stream. A treated stream 20 having a COD concentration below a predetermined threshold exits the second carbon stage 18. In certain embodiments, the treatment stream 20 includes a COD concentration of 50 mg/L or less, and in certain embodiments 30 mg/L or less.

In accordance with an aspect of the present disclosure, when the activated carbon in the first carbon stage 14 and/or the second carbon stage 18 includes an amount of waste carbon, the system 10 may further include a WAO unit 54 (also shown in fig. 7) for regenerating the waste carbon, thereby further reducing the need for carbon addition in the system 10. After separation in the

stages

14, 18, the first solids fraction 32 is directed to the WAO unit 54, as indicated by

arrows

56, 58. The WAO unit 54 may also be used to destroy biosolids from the first solids portion 32 and/or the second solids portion 50 that are delivered to the WAO unit 54 when biomass is also present in the first carbon stage 14 and/or the second carbon stage 18. The WAO unit 54 comprises one or more dedicated reactor vessels in which WAO (and biomass destruction, when present) of spent carbon material occurs at elevated temperature and pressure (relative to atmospheric conditions) and in the presence of oxygen.

In an embodiment, the WAO process is carried out at a temperature of 150 ℃ to 320 ℃ (275 ° f to 608 ° f) at a pressure of 10 to 220 bar (150 to 3200 psig). Further, in embodiments, the material introduced into the WAO unit 54 may be mixed with an oxidant (e.g., pressurized oxygen-containing gas supplied by a compressor). The oxidizing agent may be added to the material (e.g., before and/or after the material (solid portions 32 and/or 50) flows through a heat exchanger (not shown)). Within the WAO unit 54, the material therein is subjected to conditions effective to oxidize the contaminants adsorbed on the activated carbon, thereby regenerating the activated carbon material and destroying the biological material (when present). A gas fraction (off-gas) with an oxygen content can also be produced. The regenerated carbon material 60 may be recycled back to, and also receive material from, the first carbon stage 14 and/or the second carbon stage 18, as indicated by the double-headed

arrows

56, 58. To facilitate movement of the regenerated carbon material 60 through the system 10, the system may also include suitable fluid connections between components of the system 10.

By way of example, another embodiment of the system 10 that further includes a WAO unit 54 is illustrated in fig. 8, which particularly shows the flow of components including spent carbon and regenerated carbon through the system. In this embodiment, the system 10 may include: a conduit 80 between the first vessel 24 and the first separator 28 for conveying the first material 30 to the first separator 28; a conduit 64 between the first separator 28 and the first vessel 24 for recirculation of the activated carbon (and optionally biomass) therebetween; a conduit 68 between the first separator 28 and the oxidation stage 16 for conveying the first treated stream 22 to the oxidation stage; a conduit 70 between the oxidation stage 16 and the second vessel 42 for conveying the second treated stream 40 to the second vessel 42; a conduit 72 for introducing fresh activated carbon into the second container 42; a conduit 66 between the second container 42 and the second separator 46 for conveying the second material 48 to the second separator 46; a conduit 74 between the second separator 46 and the WAO unit 54 for conveying the second solids fraction 50 to the second separator 46; a conduit 76 between the WAO unit 54 and the first vessel 24 for recycling/transporting the regeneration material 60 to the first vessel; a conduit 78 between the WAO unit 54 and the second vessel 42 for recycling the regeneration material 60 to the second vessel; and/or a conduit 62 in fluid communication between the second separator 46 and the first vessel 24 for conveying at least a portion of the second solids fraction 50 including activated carbon (and optionally biomass) from the second separator 46 to the first vessel 24. It should be understood that the term "recirculation line" may be used with any of the conduits described herein, as the conduits allow for repeated movement and reuse of materials through the system.

According to an aspect of the present invention, any of the embodiments of the system 10 as described herein may further include suitable components within the flow path of any of the conduits 60-80 for removing and storing (at least temporarily) any material flowing therethrough. In an embodiment, for example and as shown in fig. 9, the system 10 may further include a purification and storage system 82 for removing and storing a portion of the first and/or second

solid portions

32, 50 including activated carbon and optionally biomass from the first and/or

second separators

28, 46. Additionally, when present, the WAO unit 54 may be in fluid communication with the activated carbon and biomass purification and storage system 82 for regenerating an amount of spent activated carbon and disrupting biomass delivered from the purification and storage system 82 to the WAO system 54. The purge and storage system 82 may include any suitable number of containers and pumps that deliver positive and/or negative pressure for storage and delivery of the desired material. For example, spent activated carbon and/or biomass may be recycled 51 to the first vessel 24. The regenerated carbon 60 may then be returned from the WAO 54 to the first vessel 24 and/or the second vessel 42. In certain aspects, in any embodiment of the system 10 as described herein, the system 10 may further comprise a polishing unit (not shown) downstream of the second carbon stage for further removing COD and/or suspended solids therefrom. The polishing unit may comprise any suitable components, such as a membrane unit, a reverse osmosis unit, an ion exchange device, and the like.

To reiterate, a system and process for reducing the overall carbon consumption required to produce low COD treated water. In certain aspects, the systems and processes described herein include an oxidation stage between the first activated carbon stage and the second activated carbon stage to reduce the overall carbon consumption within the associated system or process. In certain aspects, total carbon consumption is reduced due to an increase in biodegradable COD fraction resulting from the oxidation process (e.g., ozone treatment). As a result, a smaller amount of carbon is needed in the second stage (e.g., more biomass can be utilized). In this way, the overall carbon consumption of the system may also be reduced.

While various embodiments of the present invention have been shown and described herein, it will be obvious that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions may be made without departing from the invention herein. Accordingly, it is intended that the invention be limited only by the spirit and scope of the appended claims.

Claims

1. A water treatment system, comprising:

a first carbon stage comprising a first vessel containing at least a first amount of activated carbon configured to effectively reduce a first amount of chemical oxygen demand from a wastewater stream and produce a first treated stream having a first reduced amount of chemical oxygen demand;

an oxidation unit disposed downstream of the first carbon stage, the oxidation unit configured to oxidize a second amount of chemical oxygen demand from the first treated stream and produce a second treated stream having a second reduced amount of chemical oxygen demand;

a second carbon stage downstream of the oxidation unit comprising a second vessel containing at least a second amount of activated carbon configured to effectively reduce a third amount of chemical oxygen demand from the second treated stream and produce a third treated stream having a third reduced amount of chemical oxygen demand equal to or below a predetermined concentration limit.

2. The water treatment system of claim 1, wherein the first carbon stage, the second carbon stage, or both stages further comprise an amount of biological material therein for reducing the first amount of chemical oxygen demand and/or the third amount of chemical oxygen demand.

3. The water treatment system of claim 1, wherein the oxidation unit comprises an oxidation unit configured to subject the first treated stream to at least one of an amount of ozone, hydrogen peroxide, and ultraviolet light effective to reduce the second amount of chemical oxygen demand from the first treated stream.

4. The water treatment system of claim 1, wherein the first container is configured to remove the first amount of chemical oxygen demand from the wastewater stream and produce a first material comprising the first treated stream and a first solids portion comprising the first amount of activated carbon; and

a first separator in fluid communication with the first vessel, the first separator configured to separate the first treated stream from the first solids portion.

5. The water treatment system of claim 1, wherein the second container is configured to remove the second amount of chemical oxygen demand from the wastewater stream and produce a second material comprising the third treated stream and a second solids portion comprising a second amount of activated carbon; and

a second separator in fluid communication with the second vessel, the second separator configured to separate the third treated stream from the second solids portion.

6. The water treatment system of claim 1, wherein the first vessel comprises a first bioreactor, and wherein the first bioreactor comprises the first amount of activated carbon and a first amount of biomass therein, the first bioreactor configured to remove the first amount of chemical oxygen demand from the wastewater stream and produce a first material comprising the first treatment stream and a first solids fraction comprising the first amount of activated carbon and biomass; and

a first separator in fluid communication with the first bioreactor, the first separator configured to separate the first treated stream from the solids portion.

7. The water treatment system of claim 1, wherein the first container comprises a first membrane bioreactor comprising the first amount of activated carbon, a first amount of biomass, and a plurality of membranes therein, the first membrane bioreactor configured to: removing said first amount of chemical oxygen demand from said wastewater stream; producing a first material comprising the first treatment stream and a first solids portion comprising the first amount of activated carbon and biomass; and separating the first treated stream from the first solids portion.

8. The water treatment system of claim 1, wherein the second vessel comprises a second bioreactor, and wherein the second bioreactor comprises the second amount of activated carbon and a second amount of biomass therein, the second bioreactor configured to remove the third amount of chemical oxygen demand from the wastewater stream and produce a second material comprising the third treated stream and a second solids portion comprising the second amount of activated carbon and biomass; and

a second separator in fluid communication with the second bioreactor, the second separator configured to separate the third treated stream and the second solids portion.

9. The water treatment system of claim 1, wherein the second container comprises a second membrane bioreactor comprising therein the second amount of activated carbon, a second amount of biomass, and a plurality of membranes, the second membrane bioreactor configured to: removing the third amount of chemical oxygen demand from the second treatment stream; generating a second material comprising the third treated stream and the second amount of activated carbon and biomass; and separating the third process stream from the second material.

10. The water treatment system of claim 1, further comprising:

a wet air oxidation unit configured to regenerate an amount of spent carbon input from the first and/or second carbon stage; and

a recycle line for recycling an amount of regenerated carbon from the wet air oxidation unit to the first carbon stage and/or second carbon stage.

11. The water treatment system of claim 1, wherein the second reduced amount of chemical oxygen demand of the second treatment stream further comprises at least one of an increased biodegradable chemical oxygen demand portion and an overall reduction in chemical oxygen demand relative to the first treatment stream when the first treatment stream is oxidized in the oxidation unit.

12. A water treatment system, comprising:

a first bioreactor comprising a first amount of activated carbon and a first amount of biomass, the first bioreactor configured to remove a first amount of chemical oxygen demand from a wastewater stream introduced thereto and produce a first treated stream comprising a first reduced amount of chemical oxygen demand and a first solids fraction comprising the first amount of activated carbon and biomass;

a first separator in fluid communication with the first bioreactor, the first separator configured to separate the first treated stream from the first solids portion;

an oxidation unit in fluid communication with the first separator, the oxidation unit configured to oxidize an amount of chemical oxygen demand in the first treated stream and produce a second treated stream comprising a second reduced amount of chemical oxygen demand;

a second bioreactor in fluid communication with the oxidation unit, comprising a second amount of activated carbon and a second amount of biomass, the second bioreactor configured to remove a third amount of chemical oxygen demand from the second treated stream to produce a third treated stream comprising a reduced amount of chemical oxygen demand and a second solids fraction comprising the second amount of activated carbon and biomass; and

a second separator in fluid communication with the second bioreactor, the second separator configured to separate the third treated stream from the second solids portion.

13. The water treatment system of claim 12, further comprising a conduit between the second separator and the first bioreactor for transferring a portion of the second quantity of activated carbon and biomass from the second separator to the first bioreactor, thereby increasing activated carbon consumption in the first bioreactor and reducing the total amount of activated carbon in the system.

14. The water treatment system of claim 12, wherein the water treatment system further comprises:

an activated carbon and biomass solids purification and storage system configured to remove and/or store a portion of the first and second solids portions from the first and/or second separators; and

a wet air regeneration unit in fluid communication with the activated carbon and biomass purification and storage system configured to regenerate an amount of spent activated carbon and destroy biomass from the first and/or second solid portions.

15. The water treatment system of claim 14, wherein the wet air regeneration unit is further configured in fluid communication with the first separator for regenerating an amount of spent carbon in the first solid portion, and the system further comprises a first recycle line from the wet air regeneration unit to the second bioreactor for transporting regenerated activated carbon from the wet air regeneration unit to the second bioreactor.

16. The water treatment system of claim 12, further comprising a second recycle line between the second separator and the first bioreactor to transfer at least a portion of the second solids fraction from the second separator to the first bioreactor.

17. The water treatment system of claim 12, wherein the oxidation unit comprises an oxidation unit configured to oxidize an amount of chemical oxygen demand in the first treatment stream using at least one of ozone, hydrogen peroxide, and ultraviolet light and produce a second treatment stream comprising at least one of a second reduced amount of chemical oxygen demand and an increased biodegradable chemical oxygen demand.

18. The water treatment system of claim 12, wherein the second reduced amount of chemical oxygen demand of the second treatment stream comprises an increased biodegradable chemical oxygen demand portion relative to the first treatment stream when the first treatment stream is subjected to an oxidation process.